Myopia Research

The Longitudinal Orthokeratology Research in Children (LORIC) in Hong Kong: A Pilot Study on Refractive Changes in Myopic Control

Author: Pauline Cho, Sin Wan Cheung, and Marion Edwards

Current Eye Research, 30: 71 ¨C 80, 2005

Purpose: Myopia is a common ocular disorder, and progression of myopia in children is of increasing concern. Modern overnight orthokeratology (ortho-k) is effective for myopic reduction and has been claimed to be effective in slowing the progression of myopia (myopic control) in children, although scientific evidence for this has been lacking. This 2 year pilot study was conducted to determine whether ortho-k can effectively reduce and control myopia in children.

Methods: We monitored the growth of axial lenth (AL) and vitreous chamber depth (VCD) in 35 children (7-12 years of age), undergoing ortho-k treatment and compared the rates of change with 35 children wearing single-vision spectacles from an earlier study (control). For the ortho-k subjects, we also determined the changes in corneal curvature and the relationships with changes of refractive errors, AL and VCD.

Results: The baselinespherical equivalent refractive errors (SER), the AL, and VCD of the ortho-kand control subjects were not statistically different. All the ortho-k subjectsfound post-ortho-k unaided vision acceptable in the daytime. The residual SERat the end of the study was −0.18 ?0.69 D (dioptre) and the reduction (lessmyopic) in SER was 2.09 ?1.34 D (all values are mean ?SD). At the endof 24 months, the increases in AL were 0.29 ?0.27 mm and 0.54 ?0.27 mmfor the ortho-k and control groups, respectively (unpaired t test; p = 0.012);the increases in VCD were 0.23 ?0.25 mm and 0.48 ?0.26 mm for theortho-k and control groups, respectively (p = 0.005). There was significantinitial corneal flattening in the ortho-k group but no significant relationshipswere found between changes in corneal power and changes in AL and VCD.

Conclusion: Ortho-k can have both a corrective and preventive/control effect in childhood myopia. However, there are substantial variations in changes in eye length among children and there is no way to predict the effect for individual subjects.

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Slowing Myopia Progression with Lenses

Corneal reshaping may be a future alternative for slowing myopia progression in children.

By Jeffrey J. Walline, OD, PhD

Every eyecare practitioner has had at least one parent ask with a desperate voice, "What can we do to keep my child from becoming as nearsighted as me?" Choosing new parents is obviously not an option. Short of that, there's little evidence of any treatment options that will significantly slow the progression of myopia in children.